Gallery Thumbnail: which image should be taken as thumbail in the sidebar (preview set in NGG, first or random image)

AutoThumb parameters: if you got AutoThumb installed, the widget will use its functions to resize the image to your needs. Use a string like w=80&h=80&zc=1 here to show 80x80 square thumbnails.

Output width/height: if you don't use AutoThumb, the plugin will set the HTML attributes width & height.

Default Link Id: the widget assumes that you set up pages for each gallery and link the gallery to that page (you can use the NGG Gallery Editor to do this). If a gallery has no link set, it will use the default link (id of a page or post).